Tunnel kiln



G. W. BOOTH.

I TUNNEL KILN. APPLICATION FILED MAY 19, 1921. 1,421, 155. Patented June 27, 1922.

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GEORGE W. BOOTH, 0F ISLINGTON, ONTARIO, CANADA.

TUNNEL KIL-N.

Application filed May 19,

'Tunnel Kilns, of which the following is a specification.

This invention relates to kilns of the tunnel type, such, for example, as shown in my prior Patent No. 1,333,099 of March 9th,

1920, and my object is to devise im rove-.

ments in the firing of such kilns whic will enable gas or oil to be used in firin as effectively as solid fuels, and which wil enable the burning to be so perfectly controlled that easily spoilt ware may be as easily burnt as more rugged materials.

I attain my object by means of the constructions hereinafter described and illus- .trated in the accompanying drawings in which i Fig. 1 is a cross section through the firing zone of a tunnel kiln provided with my improvements showing the dampers set for one mode of operation at one side and for a different mode of operation at other side;

Fig. 2 a side elevation, partly in section, of parts of the preheating and firing zones of a kiln constructed in accordance with my invention; and

Fig. 3 a horizontal section on the llne ct-a in Fig. 2 of one of the walls of the kiln.

In the drawings like numerals of refer ence indicate corresponding parts in the (hiferent figures.

1 is the tunnel of the kiln which in the main may be of the construction shown in prior application hereinbefore referred to. In the top of the kiln above the tunnel 1s formed an air space 2 for preheating the air, though this forms no part of the present invention. At each side of the firing zone of the kiln is located a gas flue 3 through which any suitable gaseous or fluid fuel is supplied to be burnt in the ordinary manner. These gas flues communicate wit combustion chambers 4 formed in the walls of the furnace.

Through flues 5 the combustion chambers Specification of Letters Patent.

Patented June 27, 1922. 1921. Serial No. 470,895.

communicate with the upper part of the tunnel chamber. The openings between the flues ,5 and the tunnel chamber are preferably provided with hinged dampers 16, though these openings are easily bricked up when arranging the kiln so that the hot gases pass into the lower part of the tunnel chamber as hereinafter described. Intermediate each, combustion chamber and the tunnel chamber is formed what may be termed an equalizing, chamber 6. Each equalizing chamber communicates at its upper side with the flue 5 and a sliding damper 7 is provided whereby this openin may be more ,or less closed when desire Each equalizing chamber also communicates by means of one or more openings 8 with the interlor of the tunnel chamber at a point at or below the level of the lowerpart of the; stack of material to be burned, which as usual is supported on suitable trucks.

The equalizing chamber at each side preferably is common to a plurality of separate combustion chambers, though, of course, a continuous combustion chamber may be employed The end of the equalizing chamber adj acent the exit end of the tunnel is closed, while the other end'communicates with a flue 9 extending towards the inlet end of the tunnel. The opening between the equalizing chamber and the flue is controllable by a damper 10. The flue 9 is adapted to convey products of combustion towards a smoke stack (not shown), and as in the prior application referred to, one or more damper controlled openings 11 are formed between this flue and the interior of the tunnel.

It is desirable to supply preheated air at times to the combustion chambers 4. Itherefore provide the pip'es 12 which are provided with branches 13 leading into the combustion chambers 4. Below the branches 13 I provide sliding valves 14: which may be used. to control the sup 1y of gas to the combustion chamber. Da pers 15 are provided in the pipes 12 and these pipes are suitably connected with the air space 2 or any extension thereto.

The mode of operation is as follows. Assuming it to be desirable to have the products of combustion move in a downward direction in the tunnel chamber, the dampers 7 are closed and the dampers l0 and 16 opened. The hot products of combustion then flow through the combustion chamber, through the flues 5 and downwardly through the chamber of the tunnel, through the openings 8, and lengthwise through the equalizing chambers to the flues 9 as shown at the left hand side of Fig. 1.

In operating on certain classes of material, it is preferable to have the hot products of. combustion pass through the equalizing chambers and thence into the lower part of the tunnel chamber through the openings 8 as shown at the ri ht hand side of Fig. 1. In that case the dampers 10 and 16 are closed and the dampers 7 opened. It should be understood that the kiln will normally be operated either in one way or the other and not partly in one and partly in the other. In either case the presence of the equalizing chamber through which hot products of combustion pass has a marked effect in equalizing the temperatures within the kiln and in preventing extremely hot local temperatures, obtained with burning gaseous fluel, from prejudicially affecting the ware.

I prefer, in addition to admitting preheated air to the combustion'chamber and gas flues, to also provide means for admitting a certain amount of preheated air whenever desired to the muflie chamber. I therefore provide the pipes 17 for this purpose. The air may be supplied to these pipes in any suitable manner from the air chamber 2 or any extension thereof or from any suitable preheating apparatus.

What I claim and desire to secure by Letters Patent is:-

1. In a tunnel kiln provided with a combustion chamber in its wall beside the firing zone of its tunnel chamber; a flue forming a communication between the combustion chamber and the upper part of the tunnel chamber: an equalizing chamber between the combustion chamber and the tunnel chamber having an opening at its lower part communicating with the interior of the tunnel chamber and an opening at its upper part communicating withthe flue aforesaid; and means for causing the products of combustion to flow either from the flue aforesaid into the top of the tunnel chamber and thence into the equalizing chamber by way of its lower opening or else into the top of the equalizing chamber through its upper opening and out of its lower opening into the lower part of the tunnel chamber.

2. In a tunnel kiln provided with a combustion chamber in its wall beside the firing zone of its tunnel chamber; a flue forming a communication between the combustion chamber and the upper part of the tunnel chamber; an equalizing chamber between the combustion chamber and the tunnel chamber having an opening at its lower part communicating with the interior of the tunnel chamber and an opening at its upper part communicating with the flue aforesaid; a flue for the products of combustion with which the equalizing chamber communicates at one end; adamper controlling said communication; and a damper controlling the opening by which said equalizin chamber communicates with said first mentloned flue.

3. In a tunnel kiln provided with a combustion chamber in its Wall beside the firing zone of its tunnel chamber; a flue forming a communication between the combustion chamber and the upper part of the tunnel chamber; an equalizing chamber between the combustion chamber and the tunnel chamber having an opening at its lower part communicating with the interior of the tunnel chamber and an opening at its upper part communicating with the flue aforesaid; a sliding valve in the combustion chamber adapted to control the flow of gas into said chamber; and means for causing the products of combustion to flow either from the flue aforesaid into the top of the tunnel chamber and thence into the equalizing chamber by way of its lower opening or else into the top of the equalizing chamber through its upper opening and out of its lower opening into the lower part of the tunnel chamber. 7

4. .In a tunnel kiln provided with a combustion chamber in its wall beside the firing zone of its tunnel chamber; a flue forming a communication between the combustion chamber and the upper part of the tunnel chamber; an equalizing chamber between the combustion chamber and the tunnel chamber having an opening at its lower part communicating with the interior of the tunnel chamber and an opening at its upper part communicating with the flue aforesaid; a sliding valve in the combustion chamber adapted to control the flow of gas into said chamber; means for admitting air into the combustion chamber above the baffle; and means for causing the products of combustion -to flow either from the flue aforesaid into the top of the tunnel chamber and thence into the equalizing chamber by way of its lower opening or else into the top of the equalizing chamber through its upper opening and out of its lower opening into the lower part of the tunnel chamber.

5. In a tunnel kiln provided with a combustion chamber in its wall beside the firing zone of its tunnel chamber: a flue forming a communication between the combustion chamber and the upper part of the tunnel chamber; a damper controlling the passage of gases through said flue: an equalizing chamber'between the combustion chamber and the tunnel chamber having an opening at its lower part communicating with the incontrolling the opening by which said equalterior of the tunnel chamber and an opening izing chamber communicates with said first at its upper part communicating with the mentioned flue. 10 flue aforesaid; a flue for the products of Signed at Toronto Can. this 13th day of 5 combustion with which the equalizing cham- May 1921.

ber communicates at one end; a damper controlling said communication; and a damper GEORGE W1 BOOTH. 

